Experimenting with MiniBUD 90cm

[chapelrun]

Now that the weather is a bit better, I started working on my MiniBUD project.

Up front I want to thank walrus1957 - - - and without his help I would not have gotten this far!!

I decided for this first try at C-Band I would go with a fixed 90cm GeoSatPro dish focused on Galaxy 17 (91W). I also purchased a DMX741 from WS International and a C-band brackett from Satellite AV.

Because of LOS issues I had to move the dish to a different location. This was so I could get a clear view of 91W.

Building the walrus1957 conical scalar took about an hour and without it I could not get any signal (thus if you are going with a 90cm or 1meter MiniBUD you will almost definitely need to build one) My first one one I learned alot from and I will make a second, better one soon.

Walrus1957 Scalar Cones Construction

Very simple and inexpensive to make.
​

You can use aluminum roof flashing which costs about $10 USD for a large roll and has a nice springy nature and can be cut with scissors.

90mm ID X 260mm OD outer cone.
90mm ID X 200mm OD middle cone.
90mm ID X 140mm OD inner cone.

From the inner cone space the second and third cones 15mm apart on the slip sleeve.

Wrap the LNBF with a single layer of material 45mm deep to make a slip cylinder to attach the cones to.
​

Once I got on 91W - - - I was amazed what a difference the conical scalar rings made!!! Without it I could not get any C-Band channels but with it I got about 20. This was mainly EWTN and The Word Network plus a few other things.

Although I'm still trying different things with this setup here is what I have learned so far.

1. C-Band very possible with a 90cm dish (patience is necessary tho)
2. The LNBF is important - I got the DMX741 at the recommendation of walrus1957 and this model helped pull in the most signal possible.
3. I could not get C-Band and KU at the same time (not sure why)
4. This opens up a whole new part of FTA for me!
5. When I try again I will go with a 1.2 meter that is motorized
6. A BUD is in my future - - - already found one for free!

If you have limited space or for some other reason cannot go with a very large dish C-Band is still possible.

Here are some pix.

 

[Apprentice]

Very nice looks like something I am gong to have to venture into shortly

Glad it is working well for you.

chuck

 

[1ADAM12]

Chapelrun-

These cones work great on a dish smaller then 1 meter. 1.2 m offset dish works better with flat scalar.

I have been using them on my 90 cm offset and find C Band to be consistantly good on about 25 TP's

As for the C/ku lnbf Minimo added a 1/2" metal spacer between the c and ku lnbf and got both to work good. For details search Minimo posts.

 

[Skjellyfetti]

I am also working on a minibud dish, and using a 1.2 meter CM, a BSC621 LNB, just using C band, and a home made conical scalar ring. I used 3 plastic funnels, 8 in, 6 in, and 4 in dia, painted with RustOleum metallic paint, the kind with metal flakes in the paint and wrapped aluminum flashing around the LNB and staggered the funnels 1/2 inch apart. Unfortunately, until I find a fix for my CS7100 micro PVR power supply my project is on hold, but here are some of pictures of the conical scalar ring setup on the LNB.

 

[chapelrun]

I'm curious - - - where did you buy the funnels

I like the looks of the funnels. :up

Where did you find them?

 

[McGuyver]

I like the looks of the funnels. :up

Where did you find them?

Funnel sets are sold at a variety of stores including the grocery markets, they include the various sizes you see in the photos. Shouldn't be hard to find

 

[Skjellyfetti]

I like the looks of the funnels. :up

Where did you find them?

WalMart $1.88 for the three of them and $4.00 for the paint and some JBWeld to glue it up.

 

[Musher]

Have any of you tried this set up at 121.0W C-Band because there are some channels on that bird I would like to get. Have been thinking about try'in this Mini Bud set up out.

Musher

 

[Mr Tony]

any channel in specific?

 

[Musher]

Iceberg the channel I was wondering about was America One. Galaxy 23, On tp 18 4052 V . They have a very low power station in Milwaukee that carries it but can't get it were I live. They have some very good shows on that Channel. I do have a spare 90cm dish and was thinking about trying it this spring with the Mini Bud set up.
Musher

 

[WSInternational]

I am also working on a minibud dish, and using a 1.2 meter CM, a BSC621 LNB, just using C band, and a home made conical scalar ring. I used 3 plastic funnels, 8 in, 6 in, and 4 in dia, painted with RustOleum metallic paint, the kind with metal flakes in the paint and wrapped aluminum flashing around the LNB and staggered the funnels 1/2 inch apart. Unfortunately, until I find a fix for my CS7100 micro PVR power supply my project is on hold, but here are some of pictures of the conical scalar ring setup on the LNB.

I like the looks of the home made conical scalar ring. Wonder how it performs.

 

[Mr Tony]

Iceberg the channel I was wondering about was America One. Galaxy 23, On tp 18 4052 V . They have a very low power station in Milwaukee that carries it but can't get it were I live. They have some very good shows on that Channel. I do have a spare 90cm dish and was thinking about trying it this spring with the Mini Bud set up.
Musher

It might be tough. You can try. I wasnt able to get it here in Minneapolis on the 4 footer. The 6 footer yes but not the 4 footer

 

[Musher]

Iceberg, if there was anybody to ask this question it was You. I will give it a try in about a month. Thanks!
Musher

 

[tamuin]

> 3. I could not get C-Band and KU at the same time (not sure why)

Could you elaborate on this? Were you able to get KU when you were connected just to the KU side of the DMX741 or were not able to get KU at all with the DMX741.

Nice pictures and thanks for the info.

 

[chapelrun]

Good Question

I guess I said it wrong - - - I never did get KU Band with the DMX741.

I did get the signal levels up in the 70's but never could get any quality for KU. Since I was really going for C-Band I did not worry too much about it but this really did slow me down a bit because I thought I would be able to use KU to point the dish.

I will try again tonight and see if I can get any KU Band from 91W with this LNBF. I thought it must be SKEW but I've tried almost every possible with SKEW and still don't get any quality for KU Band.

Of course, I'm sure the dish is correctly pointed to 91W because one of the C-Band TP's shows almost 40% Quality.

 

[WSInternational]

I guess I said it wrong - - - I never did get KU Band with the DMX741.

All the C/Ku LNBF you see on the market right now, including the DMX741, DMX741U, BSC621, or the universal version, are designed to work with Prime Focus dishes and not offset dishes. No matter which model C/Ku LNBF you use on an offset dish, you will get either no or poor reception on Ku. Check out this modification: http://www.satelliteguys.us/free-air-fta-discussion/195498-bsc621-ku-s-q-improvement.html

 

[McGuyver]

I thought that I read somewhere in this Forum something about placing a 1/2 inch metallic spacer between the feedhorn body and the Ku lnb and they say it works on offset dishes.
Don't quote me as I said... "I thought" lol
Check it out, Anole should know about this, he's good about keeping info

 

[Anole]

There was such a mod someone was talking about.
I don't recall the details, so apparently it didn't leave me convinced.
... or maybe there was supposed to be follow up, and I missed it.
edit: in Robby's post above, he linked to the thread in question.


Just why the CK1's, 741's, and 621's of the world don't do as well on Ku, at least on prime focus dishes was due to their narrow view of the dish, I thought.
So, the C-band feed saw the entire dish with an F/D of .3 or .4, but the Ku portion acted like it had an F/D of .6 - .7, and only saw the center.
Properly installed and centered, they -can- do quite well, though.

So anyway, you'd think the Ku would see an offset dish just fine.
Never seemed to work that way.

Another factor that was brought up, had to do with the Ku feed decreasing the C-band signal just a little, compared to a C-only LNBF.
Not sure which of these points are true and which are conjecture, so you're on your own.